Recently, the technical development to the improvement in a performance of smaller droplet, higher drive frequency and more number of nozzle is continued in order to make the record characteristic more advanced in an ink jet record system. And image recording is performed by ejecting liquid from an ejection opening as small droplet which adheres to the recording medium typified by paper.
Here, a surface treatment is becoming more important to maintain ejecting performance by keeping ejecting opening surface as same condition at any time. Moreover, it is common to wipe off the ink which remained on the surface by e.g. rubber blade periodically to maintain the condition of the ejecting opening surface in an ink jet head. A liquid repellent material is demanded for easy wiping, and wiping durability.
Moreover, when the liquid repellent layer is prepared on the surface, the liquid repellent layer needs to adhere to its lower layer, and the problem of peeling off of liquid repellent layer may occur. Since the ink used for an ink jet head is not neutral in many cases, it is also required that the liquid repellent material should have durability against ink and have adhesion power to a nozzle. In addition to preventing peeling, from a viewpoint of simplification of manufacturing process and cost reduction, the process is desired that the nozzle material and liquid repellent layer is prepared all at once. That is, nozzle material itself is desired to have liquid repellency.
Various methods have so far been indicated as the liquid repellent processing on the surface of a nozzle in the ink jet head. However, most of them were just the surface treatment of the formed nozzle, and the nozzle material itself did not have the liquid repellent nature.
The surface treatment method which used the fluoride containing silane compound is indicated in Japanese Patent Publication No 10-505870 and U.S. Pat. No. 6,283,578.
However, these surface treatments were aimed at liquid repellent nature grant, and were not those in which the liquid repellent material itself has patterning nature. Moreover, the liquid repellent materials that had photosensitivity were indicated by Japanese Patent Application Laid-Open No. 11-322896, Japanese Patent Application Laid-Open No. 11-335440, and Japanese Patent Application Laid-Open No. 2000-26575. These materials could not form the solid structure like a nozzle.
When the fluorine-containing compound which is a typical liquid repellent material is added to resin, it is well-known phenomenon that fluorine-containing group is arranged in the surface for its low surface energy, and presenting liquid repellency.
However, since fluorine-containing compounds generally have low dissolubility to other resin, it was difficult to mix with photosensitive resin and to use together.
Although the block copolymer having fluorine-containing group was indicated in Japanese Patent Application Laid-Open No. 2002-105152 as a coating composition, it could not be applied to the high-precision patterning like nozzle forming. Japanese Patent Application Laid-Open No. 2002-292878 referred to the orifice plate having nozzle structure, which was made of fluorine-containing resin. Since fluorine-containing resin did not have photosensitive characteristic corresponding to patterning by photo-lithography, the nozzle had to be formed by dry etching etc. Furthermore, the inside of ink passage of a nozzle needs to be hydrophilic in order to obtain the ejecting performance, hydrophilic processing needed to be performed inside of the ink passage and the adhesion side with basis material and so on.
Cationically polymerizable resin composition, which included fluorine-containing compounds, was indicated by Japanese Patent Application Laid-Open No. 8-290572. However, the purpose of this invention was the rate reduction of water absorption of material, not liquid repellency. Since the compound in this invention has hydroxyl group for dissolubility with resin composition, the composition did not show liquid repellency.
U.S. Pat. No. 5,644,014, EP B1 587667 and Japanese Patent Publication No. 3306442 referred to the liquid repellent material comprising hydrolysable silane compounds which had fluorine-containing group. Although the above-mentioned material is indicating the photo curability which was derived from photo radical polymerization, it is not mentioned about pattern formation using photo lithography technology nor the application to an ink jet head.